Human blood vessels often become occluded or blocked by plaque, calcified tissue, thrombi, other deposits, emboli, etc., which reduce the blood carrying capacity of such vessels. Should a blockage occur at a critical place in the vascular system of a patient, serious and permanent injury, and even death, can occur. To prevent damage in the vascular system, some form of medical intervention is usually performed when a buildup or significant occlusion is detected.
Laser-based catheter devices are often used to ablate such buildups or occlusions. Laser light is sent down optical fibers of a laser catheter to perform laser ablation and, in some cases, visualization of vascular structure. Additionally, fluoroscopy presents a two-dimensional view and, in cases where contrast agents are injected, provides indirect visualization of vascular structure. Fluoroscopy is a procedure that may introduce undesirable radiation exposure and risks associated with the use of contrast agents, and may also provide insufficient imaging or feedback for clinicians to clearly understand the interface between the catheter device and the vascular system.
Accordingly, with existing medical interventions, there is a risk created both by lack of effective techniques for visualizing and understanding the interface between a catheter and vascular structure and by lack of effective techniques for strictly controlling ablation based on such visualization and understanding. For example, there is a risk of errors in determining whether or not particular material should be ablated and errors in determining how much undesired material remains during or after ablation. There is consequently a risk of overtreatment, including a risk of errors in ablating material that is not needed or desired to be ablated, at times even to the point of tearing of tissue, and errors in not ablating material that is needed or desired to be ablated.